Apparatus for automatically controlling the speed of a rewind mandrel



March 12, 1968 o. oLsEN 3,373,332

APPARATUS FOR AUTOMATICALLY CONTROLLING THE SPEED OF A REWIND MANDRELFiled June 25, 1965 5 Sheets-Sheet l INVENTOR oLUF oLsE N ATTORNEY March12, 1968 o. oLsEN APPARATUS FOR AUTOMATICALLY CONTROLLING THE SPEED OF AREWIND MANDREL C5 Sheets-Sheet 2 Filed June 25, 1965 QUE m0 DUEUZOTrUZDLZD OF IISVOLTS A.C.

|20 VOLTS |NvEN-roR oLuF oLsEN ATTORNEY March l2, 1968 o. oLsx-:N

APPARATUS FOR AUTOMATICALLY CONTROLLING THE SPEED OF A REWIND MANDRELFiled June 25, 1965 5 Sheets-Sheet 3 A@ @Y www@ INVENTOR OLUF OLS E NUnited States Patent Oiiiice 3,373,332 Patented Mar. 12, 1968 APPARATUSFOR AUTOMATICALLY CONTRL- LING THE SPEED F A REWIND MANDREL Oluf Olsen,Cranford, NJ., assigner to John Dusenbery JCompany, Inc., Clifton, NJ.,a corporation of New ersey Filed June 25, 1965, Ser. No. 467,067 11Claims. (Cl. 318-396) ABSTRACT 0F THE DISCLOSURE Apparatus forautomatically reducing the speed of rotation of a motor-driven mandrelin correspondence with the increased diameter of a roll of materialwound upon a core carried by the mandrel. A switching device,mechanically-coupled to the mandrel, produces voltage pulses uponrotation of the mandrel. A predetermined number of the voltage pulsesare converted into a control voltage which actuates a control device foreffecting a predetermined decrease in the speed of the motor.

This invention relates to a machine for winding a plurality ofrelatively narrow strips of material on individual cores carried by amandrel and more particularly to apparatus for automatically controllingthe mandrel speed in correspondence with the increase in diameter of thewound rolls.

In machines of the class to which this invention is directed, arelatively wide web of material, such as paper or plastic, is slit intoa plurality of narrow strips, which strips are then Wound into roll formon individual cors mounted on a positively driven shaft, or mandrel. Onevariable factor which effects the winding of the strips is the normalvariation in the thickness, or gauge, of the particular material. Thisresults in the diameter of some wound rolls increasing at a greater ratethan others. As the diameter of the wound rolls increases, therotational speed of the core must decrease since the strips pass to thecores form a pull roll having a constant speed of rotation. Accordingly,it is the practice to mount the cores on the common mandrel vin suchmanner that each core can slip on the mandrel independently of the othercore and to an extent corresponding to the tension of the associatedstrip of material. Generally, this is accomplished by inserting corespacer rings over the mandrel and between each core. Such spacer ringsare individually keyed to the mandrel and the Iassembly of cores andspacer rings is clamped, axially, by suitable loading means carried bythe mandrel ends. Thus, the spacer rings are positively driven by themandrel 4while eac-h core is free to slip relative to the mandrel as thetension of the associated strip exceeds the frictional restraining forceexerted against the core ends by the adjacent spacer rings. Thisarrangement is commonly referred to in this art as differential winding.

The differential Windin-g arrangement is only a partial solution of theproblem of providing uniformly wound rolls of the strip material. As thediameter of the wound rolls increases, there is a corresponding increasein the slippage of the cores, which results in a heating of the spacerrings and cores and mandrel vibrations. The heating of the coresadversely affects certain materials and mandrel vibrations result inwound rolls of poor quality. Further, the heat expansion of the coresand spacer rings results in an increase in the coefficient of frictionbetween these relatively rotatable members, thereby increasing heatgener'ation. The net result is a decrease in the slippage of the coresrelative to the mandrel and an increase in the tension of the stripsbeing Wound thereon.

In the case of very thin material, a tearing through of the strip oftenoccurs. It is, therefore, highly desirable to reduce the speed of theImandrel as the diameters of the wound rolls increase, thereby tomaintain a substantially constant slippage between the cores and themandrel throughout the entire winding operation. This can be donemanually, in steps, or automatically by an arrangement which includes asensing member in riding engagement with the outer convolution of thestrip being Wound on a selected core. Such prior automatic arrangementsgenerally are critical in operation and may result in an undesirablemarking or scoring of the material.

An object of this invention is the provision of an arrangement forautomatically controlling the rotational speed of a mandrel in adifferential rewinding machine thereby to produce wound rolls of uniformhigh quality.

An object of this invention is the provision of apparatus forprogramming the speed of the rewind mandrel of a differential rewindingmachine in correspondence with the increased diameter of the woundrolls,

An object of this invention is the provision of a winding machine havinga positively driven mandrel carrying a plurality of rewind cores uponwhich strips of material are to be wound, sensing means producingsignals corresponding to the number of rotations of the mandrel, andcontrol means responsive to the signals to effect a chan-ge in themandrel speed.

An object of this invention is the provision of a differential windingmachine Ihaving a positively driven mandrel carrying a plurality ofcores upon which Strips of material are to be wound, sensing meanscoupled to the mandrel and producing a predetermined num-ber of voltagepulses for each revolution of the mandrel, control means controlling therotational speed of the mandrel, and means responsive to a predeterminednumber of the volta-ge pulses and effecting actuation of the controlmeans.

T-hese and other objects and advantages will become apparent from thefollowing detailed description when taken with the accompanyingdrawings. It will be understood, however, that the drawings are forpurposes of illustration and are not to be construed as defining thescope or limits of the invention, reference being had for the latterpurpose to the claims appended hereto.

In the drawings wherein like reference characters denote like parts inthe several views:

FIGURE 1 is a diagrammatic representation of a differential windingmachine incorporating control apparatus in accordance with thisinvention; and

FIGURES 2 and 3 are schematic circuit diagrams of the apparatus.

Referring now to FIGURE 1, there is shown a mandrel 10 having alongitudinal keyway 11 formed therein, said mandrel carrying a pluralityof rewind cores and core spacer rings such as the cores 12, 13 and thespacer rings 14. Each spacer ring is provided with a key disposed in themandrel keyway. Although not shown in the drawing, the assembly of coresand spacer rings is clamped, axially, by conventional loading meanscarried by the mandrel, whereby the ends of the spacer rings are pressedagainst the ends of the cores, the latter generally being made ofcardboard.

Before the start of the winding apparatus, the ends of the cut strips15, 17 of material are secured to the associated cores, as by adhesivetape. These strips have been formed from a wide web of the material by acontinuous slitting operation and adjacently-disposed strips are passedaround spaced, parallel pull rolls. Specifically, the odd numberedstrips pass over the pull roll 18 whereas the even numbered lstrips passover the other similar pull roll, not shown, whereby the spacing betweenthe cores 12 and 13 corresponds to the width of the cut strips. The pullrolls are driven at a constant speed from the main drive shaft of themachine. The mandrel lll, driven by a rewind motor 19, initially isrotated at a predetermined speed to maintain a tension on the strips asthey are being wound, thereby providing tightly wound rolls. Thus, eachcore will slip, relative to the mandrel, in correspondence with thetension of the strip being wound thereon and this tension increases withthe diameter of the rewound roll. For example, if the thickness of thestrip is slightly greater than that of the strip 17, the diameter of theroll will increase at a greater -rate than the roll 21, resulting in anincreased slippage of the core l2 as compared to the core 1.3. Suchchange in the slippage of the individual cores compensates for thenormal thickness variations of the particular material and results inthe rolls being wound to a substantially uniform tightness.

1t will be apparent that as the diameter of the rewound rolls increasesthe tension of each strip increases and, therefore, there is acorresponding increase in the slippage of all cores relative to themandrel. This results in an undesirable heating of the cores and, often,in mandrel vibrations. Consequently, it is highly desirable to reducethe mandrel speed, during the winding operation, preferably in a mannerso as to maintain a substantially constant slippage of the cores fromthe beginning to the end of the rewinding cycles. Further, it isdesirable to effect such change in the mandrel speed by means which donot involve physical contact with the material in order to precludepossible marring or scratching thereof. This is accomplished by theapparatus now to be described.

Mechanically-coupled to the mandrel is an electrical contactor 24, whichis a single pole, rotary switch having equal on and off time periods aswill be described hereinbelow. The switch contacts are connected in aconventional circuit, comprising a capacitor and a source of DC.voltage, in such manner that the capacitor is rapidly charged when thecontacts are open and the capacitor is discharged when the contacts areclosed. This produces voltage pulses a having a frequency depending uponthe speed of rotation of the mandrel. The voltage pulses a are appliedto a No. l flip flop circuit which converts these pulses into squareWave voltage pulses b having a predetermined constant amplitude andwidth.

A capacitance decade box 26 comprises three or more multi-contact,rotary switches having indicator knobs 27, 28 and 29 cooperating withscales preferably calibrated in factors relating to material thickness.These knobs are set to the nominal thickness of the particular materialto be processed, thereby selectively connecting the internal capacitorsto present a predetermined capacitance value to the uni-junction circuit30. The voltage pulses b charge these capacitors and when the capacitorsare charged to a predetermined level, the uni-junction circuit ires toproduce a voltage pulse c. Such voltage pulse is converted to a squarewave pulse d by the No. 2 flip-flop circuit 3l, which pulse is amplifiedby the amplifier 32 and applied to a stepping motor 33. It may here bepointed out that a control box 34 carries a pushbutton switch 35 and asignal lamp 36, depression of the switch effecting a resetting of theapparatus and the lamp becoming energized when the resetting functionhas been completed.

Each amplified voltage pulse applied to the stepping motor 33 causes theoutput shaft 37 to rotate, say, onetwentieth (l/go) of one revolution,such shaft being coupled to a speed reducer 38 having an input to outputgear ratio of, say, 18 to l. The output shaft 39, of this speed reducer,carries a sprocket wheel 40 and is directly coupled to a shaft 4l, whichshaft is, in turn, coupled to a shaft 42 through an electro-magneticclutch 43, the latter shaft 42 also carrying a sprocket Wheel 44. Asecond speed reducer 45, having a ratio of, say, 2.25 to 1, has an inputshaft 46, carrying the sprocket wheel 47, and an output shaft 48 coupledto a shaft 49 by a second electro-magnetic clutch 50. The shaft 49carries a sprocket wheel 51 and is directly coupled to the shaft of apotentiometer 52, which potentiometer may be either a single or a gangtype. The aligned sprockets 40 and 47 are coupled by a drive chain 54and the other sprockets 44 and 5l are coupled by a drive chain 55.Rotation of the arm of the potentiometer 52 changes the speed of theD.C. rewind motor 19 driving the mandrel.

Only one of the electro-magnetic clutches 43 and 5t) is energized at anygiven time. When the clutch 50 is energized, the rotatable arm of thepotentiometer 52 is rotated in a direction to insert ohmic resistanceinto the circuit of the mandrel drive motor 19, thereby reducing thespeed thereof. The rate at which this motor slows down depends,essentially, upon the combined ratios of the two speed reducers 38 and45, since the rotatable arm of the potentiometer now is coupled to theshaft of the stepping motor 33 through both speed reducers. On the otherhand, when the clutch 43 is energized, the potentiometer arm is coupledto the shaft of the stepping motor only through the speed reducer 38.Under this condition, the potentiometer arm is rotated in the reversedirection and at an increased speed.

Now, during the winding operation, the clutch 50 is energized and theclutch 43 is deenergized. Thus, the stepping motor 33 drives thepotentiometer shaft through both of the speed reducers 38 and 45, and,in the specific example here given, one revolution of the potentiometershaft requires l8 2.25=40.5 revolutions of the stepping motor shaft.Since one revolution of the stepping motor shaft is effected by theapplication of 20 pulses to such motor, and assuming a l to l ratiobetween the number of pulses a (generated by the contactor 24) and thenumber of pulses c (applied to the ip-flop circuit 31), the full rangeof speed adjustment of the mandrel drive motor 19 will correspond to40.5 20=80l convolutions of the material wound on the cores. If, now,the decade box 26 is adjusted to provide, say, a 50 to 1 ratio betweenthe pulses a and c such speed range adjustment of the mandrel drivemotor will correspond to 40,050 convolutions of the material on thecores. The actual range of mandrel speed adjustment will depend upon theamount by which the mandrel speed must be reduced to eect a properwinding of rolls to a predetermined maximum diameter and the rate atwhich such speed adjustment is made will depend upon the thickness ofthe particular strips being rewound. Generally, a mandrel speedreduction of 30%, from its initial speed at the start of the windingoperation, will be satisfactory for coils wound to a diameter of 10inches on cores having an outside diameter of 3 inches.

To reset the apparatus, after the completion of the winding operation,the push button 35 is depressed. This results in the deenergization ofthe electro-magnetic clutch 50 andthe energization of the clutch 43,thereby coupling the potentiometer arm only to the speed reducer 38. Atthe same time, the uni-junction circuit 30 is converted into arelaxation oscillator thereby to apply a rapid succession of pulses tothe stepping motor for the return of the potentiometer 52 to its initialor starting position at a rapid, predetermined rate.

Reference now is made to FIGURE 2, which is a schematic, partial circuitdiagram of the apparatus and including a diagrammatic representation ofcertain other components for controlling the speed of rotation of themandrel drive motor. The apparatus is energized upon closure of the lineswitch 60, thereby applying volts A C. across the main leads 61 and 62,the lead 61 having a suitable fuse 63 inserted therein. This energizesthe transformers 64 and 65. The center-tapped secondary winding of thetransformer 64 has connected thereto rectiers 66 and a conventionalfilter network, thereby providing 27 volts DC. across the terminals 67and 68, such voltage being regulated by a Zener diode 69. The secondarywinding of the transformer 65 is connected to the input junctions of arectifier bridge 70. One output junction of the bridge is connected tothe terminal 71 and the other output junction is connected to theterminal 68. A conventional filter network is connected across thebridge output junctions and the potential across the terminals 68 and 71is 50 volts D.C.

Closure of the switch 72 connects the operating coil of the power relay73 across the line leads 61 and 62, said relay having two sets ofsingle-pole, double-throw contacts. When this relay is in the energizedcondition the lower contacts 74 and 75 are closed, thereby connectingthe main drive motor 76, of the machine, across the line leads 61 and62. It may here `be pointed out that this motor furnishes the powerrequired to unwind a web of material from a supply roll, slit such webinto a plurality of relatively narrow strips and move such strips to therewind cores by pull rolls, such as the pull roll 18 shown in FIGURE l.The upper set of relay contacts, namely, the movable contact 77, theback stationary contact 78 and the front stationary contact 79, areconnected into the uni-junction circuit for purposes which will bedescribed hereinbelow with specic reference to FIGURE 3.

The closure of the switch 80 completes the circuit between the mandreldrive motor 19 and a source of 120 volts D C., such circuit being tracedas follows: lead 81, switch 80, potentiometer 52, iixed resistor 83,motor 19 and lead 84. The rotatable arm of the potentiometer is shown inits starting position, in which position there is a minimum totalresistance in the motor circuit, whereby the motor runs at apredetermined, maximum speed. It will be understood that the drive shaftof this motor is mechanically coupled to the mandrel (see FIGURE 1)through a suitable gearing system, whereby the initial speed of rotationof the rewind cores is such as to maintain a predetermined amount oftension on the strips of material being wound thereon.

A second power relay 85, having three sets of contacts, normally is inthe illustrated, deenergized condition. In such deenergized condition,the electro-magnetic clutch 50 is energized by 27 volts D.C., thecircuit being traced as follows: lead 87, the normally-closed relaycontacts 88 and 89, lead 90, the normally-closed contacts of a limitSwitch 91, lead 92, the operating coil of the clutch 50 and the lead 93.The energization of this clutch mechanically couples together the shafts48 and 49, the shaft 48 being the output shaft of the gear reducer 45(see FIG- URE 1). Thus, the shaft 49 will be rotated in a step-bystepmanner in accordance with the application of voltage pulses to thestepping motor, as has been described hereinabove. This results in arotation of the arm of the potentiometer 52 to insert additionalresistance into the circuit of the mandrel drive motor 19. Suchadditional resistance is inserted into the motor circuit at apredetermined rate in correspondence with the increase in the diametersof the wound rolls carried by the mandrel.

The second set of contacts 95 and 96, of the relay 85, are connectedinto the uni-junction circuit for purposes which will be describedhereinbelow. The third set of relay contacts 97 and 98 constitutelock-in contacts for retaining the relay in the energized condition uponmomentary closure of the normally-open contacts of the reset switch 34,as will be described in more detail hereinbelow.

As shown in FIGURE 2, the apparatus is in the starting position, thatis, at the start of the winding operation. In such starting position,the lobe on the cam 100, carried by the shaft 49, causes the centercontact 101, of a single-pole, double-throw switch 102, to be inengagement with the contact 103. When the contacts 101 and 103 areclosed, the signal lamp 36 is energized by the A.C. line voltage,thereby indicating that the apparatus has been fully reset and is incondition for the start of the winding operation. As the windingoperation begins, the cam 100 rotates in the indicated -direction andthe center switch contact 101 becomes disengaged from the contact 103and engages the contact 104, thereby connecting the line lead 6 61 toone of the normally-open contacts of the reset switch 34.

As the winding operation progresses, more and more of the potentiometerresistance is inserted into the circuit of the mandrel drive motor 19causing a corresponding decrease in the motor speed. At the same time,the lobe on the cam 100 rotates toward the limit switch 91. Normally,the cam rotates some 300 degrees, from' the illustrated position, fromthe start to the completion of the winding operation. In the event thewinding operation continues beyond a predetermined maximum limit, thecam lobe opens the contacts of the limit switch 91, thereby opening thecircuit to the electro-magnetic clutch 50. This disconnects therotatable arnr of the poteniometer from the output shaft 48 (of the gearreducer) so that the arm cannot move beyond the limit of the resistancewinding.

Assuming, now, that the winding operation has been completed, theoperator opens the motor switches 72 and thereby stopping the machine.To reset the control apparatus, the operator depresses the reset switch34 to momentarily close the contacts thereof. This results in theenergization of the operating coil of the relay 85, the circuit beingtraced as follows: line lead 61, lead 105, the now-closed contacts 101and 104 (of the switch 102), lead 106, the closed contacts of the resetswitch 34, the operating coil and the lead 107. Since the lower set ofrelay contacts 97 and 98 are connected in parallel with the contacts ofthe reset switch, the closure of these relay contacts locks the relay,electrically, in the energized condition. When this relay is in theenergized condition, the upper movable contact 89 is engaged with thefront stationary contact 108. This results in the deenergization of theelectro-magnetic clutch 50 and the energization of the clutch 43. Hence,the shaft 49 (connected to the rotatable arm of the potentiometer) nowis disconnected from the shaft 48 and connected to the shaft 41 throughthe drive chain 55. The shaft 41 is coupled to the output shaft of thespeed reducer 38 (see FIGURE l) which shaft rotates in a directionreverse to that of the output shaft 48 of the other speed reducer 45,upon the application of voltage pulses to the stepping motor. As will bedescribed hereinbelow, the potentiometer arm now is rotated back towardits initial position at a predetermined, increased speed. When the cam100 returns to its original, starting position, the center contact 101,of the switch 102, becomes disengaged from the Contact 104 and engagedwith the contact 103. The opening of the contacts 101 and 104 opens thecircuit to the operating coil of the relay 85, whereby this relayreturns to the deenergized condition. The closure of the contacts 101and 103 results in the energization of the signal lamp 36 to indicatethat the resetting operation has been completed.

It may here be pointed out that the motor control switches 72 and 80,the line switch 60, the reset switch 34 and the signal lam-p 36 arelocated at the operating station of the machine. All other components ofthe apparatus, with the exception of the rotary contact which is coupledto the rewind mandrel, may be housed within a suitable cabinet attachedto the machine or located at a remote position.

Reference now is made to the circuit diagram of FIG- URE 3 wherein thereis shown the mandrel drive motor 19, the rotational speed of which iscontrolled by the position of the arm of the potentiometer 52. Through asuitable gearing system, not shown, the motor drives the mandrel 10 at apredetermined, maximum speed at the start of the winding operation. Therotary contactor 24 is mechanically coupled to the mandrel and itscontacts open and close, say, three (3) times for each revolution of themandrel. When the contactor is closed, it discharges the capacitor 110.When the contactor is open, the capacitor is recharged through theresistor 111, which provides a sharp signal pulse to the input circuitof the No. 1 ilip-llop circuit 25.

The function of the ilip-op circuit 25 is to provide a square pulseoutput signal, having a definite height and width, for each input pulse.Such circuit is a conventional mono-stable (one shot) multi-vibratorycomprising two emitter-coupled transistors 112 and 113 biased so thatthe transistor 113 normally is in the conducting state and thetransistor 112 normally is in the non-conducting state. Upon the receiptof an input signal pulse, which occurs when the contactor 24 opens, thetransistor 112 is triggered out of its stable state, regenerationoccurs, and the astable state will exist for a given time perioddetermined by the values of the resistor 114 and the capacitor 115.After the capacitor 115 has become charged, the transistor 112 returnsto its conducting state.

The output voltage pulses produced by the flip-flop circuit 25, having aconstant amplitude and width, produce corresponding current pulses inthe collector circuit of the transistor 116 (in the uni-junction circuit30), which pulses charge the capacitors contained in the decade box 26.When the voltage across these capacitors reaches the peak point voltageof the uni-junction transistor 117, this transistor tires and dischargesthe capacitors. The cir cuit parameters are such that from 3 to 240current pulses will be stored by the capacitors before the voltageapplied across the uni-junction transistor reaches the peak pointvoltage, the actual number of such pulses being determined by the totalcapacitance connected across the leads 118 and 119. Such totalcapacitance is determined by the setting of the rotary switches 27, 28and 29 of the decade box 26. The rotary contact of each switch hasconnected thereto a conventional knob associated with a dial marked inmaterial thickness values or in arbitrary values. In the latter case,the setting of the three switches, for a given material thickness, willbe obtained from a reference chart. In any event, the setting of theseswitches establishes the number of pulses to be stored by the capacitorsof the decade box before the uni-junction transistor res.

Referring specifically to the uni-junction circuit, attention isdirected to the contacts 95 and 96 and the contacts 77, 78 and 79constituting a single-pole7 doublethrow switch. The contacts 95 and 96are the similarlyidentified, normally-open contacts carried by the powerrelay 85 shown in FIGURE 2, whereas the contacts 77, 78 and 79 arecarried by the relay 73. As has been described hereinabove, during thewinding operation, the relay 73 is energized and the relay 85 isdeenergized. Thus, during the winding operation, the contacts 95 and 96are open, whereas the contacts 77 and 79 are closed, and such contactpositions are shown in FIGURE 3. Consequently, the emitter of theuni-junction transistor 117 is connected to one side of the capacitorsof the decade box by the lead 119. The base of this transistor isconnected directly to the voltage terminal 68, to which terminal theother side of the decade box capacitors also are connected by the lead118. Successive output current pulses of the transistor 116 eventuallycharge these capacitors to the peak point voltage of the uni-junctiontransistor, thereby causing such transistor to lire.

When the uni-junction transistor fires, the resulting voltage dropacross the input circuit of the transistor 120, of the flip-flop circuit31, causes this transistor to switch from the non-conducting to theconducting state. This flip-flop circuit is the same as the circuit andproduces corresponding output voltage pulses but of predetermined heightand width. Such output voltage pulses are applied to the conventionalpulse amplier 32 having an output transformer 121. The voltage pulsesgenerated in the center-tapped secondary winding of the transformer areapplied to the stator windings 124 and 125 of the stepping motor 33,which motor is a conventional high torque, uni-directional motor havinga low inertia rotor and permanent magnets in the stator. The statorwindings are reversed with respect to each other and the rotor 126 isrotated one-twentieth of a revolution in response to each voltage pulseapplied to the stator windings by the amplifier 32. The rotor 126 iscoupled to the shaft of the potentiometer 52 through the speed reducersand electro-magnetic clutches, here identified by the numeral 127. Thepotentiometer arm is coupled to the rotor 126 through both of the speedreducers 3S and 45 (see FlG- URE l), since the clutch 50 is energizedand the clutch 43 is cle-energized during the winding operation.

As has been described hereinabove, when the winding operation has beencompleted, the relay 73 (see FIGURE 2) is deenergized upon the openingof the switch 72 by the operator. This results in the opening of therelay contacts 77 and 79 and the closing of the relay contacts 77 and73. Also, upon momentary closure of the contacts of the reset switch 34(see FIGURE 2), the relay S5 is energized and locks in electrically,thereby closing its contacts 95 and 96. Under these conditions, that is,during the resetting of the control apparatus, the contacts 95 and 96,of the uni-junction circuit (see FlGURE 3) are closed and the contact 77is transferred from engagement with the contact 79 to engagement withthe Contact 7S. Now, the emitter of the uni-junction transistor 117 isdisconnected from the capacitors in the decade box 26 and connected tothe resistor 130, the other end of this resistor being connected to thevoltage terminal 67. The uni-junction circuit now operates as arelaxation oscillator at a frequency determined by the values of theresistor 130 and the capacitor 131, which frequency is approximately 33cycles per second. Square waves, having a corresponding frequency, arenow produced in the output circuit of the flip-flop circuit 31,amplified by the amplifier 32 and applied to the stepping motor. At thisfrequency, the stepping motor runs as a synchronous motor. Also, duringthe resetting operation, the electro-magnetic clutch 43 is energized(see FIGURE l) and the clutch 50 is deenergized, whereby the shaft ofthe potentiometer 52 is coupled to the stepping motor rotor only throughthe gear reducer 38. Hence, the potentiometer arm is returned rapidly toits initial, 0r starting position, as determined by the lobe on the cam100 (see FIGURE 2), which lobe opens the contacts 191 and 104, of theswitch 162, and closes the contacts 101 and 103. Opening of the contacts101 and 104 removes power from the operating coil of the relay resultingin the opening of the relay contacts and 96, The opening of thesecontacts 95 and 96 (see FIGURE 3) opens the circuit to the emitter ofthe uni-junction transistor, the circuit ceases to oscillate and thestepping motor is stopped. At the same time, the closure of the contacts101 and 103, by the cam lobe (see FIGURE 2), results in the energizationof the signal lamp 36, indicating the resetting cycle has beencompleted. Upon removal of the wound rolls, reloading the mandrel withnew cores and securing thereto the ends of the cut strips, the machineis in condition for the next winding operation.

In summary, the apparatus for controlling the speed of the mandrel is incondition for proper operation the moment the main drive motor of themachine is energized. When the mandrel drive motor is energized, therotary contactor, coupled to the mandrel, opens and closes apredetermined number of times during each revolution of the mandrel.This produces signal pulses which are related, frequency-wise, to thespeed of rotation of the mandrel. These signal pulses are converted intocorresponding square wave pulses having a constant, predetermined heightand width. These square wave pulses are converted into correspondingcurrent pulses for charging the capacitors in the decade box. When thevoltage level of the charged capacitors equals the peak voltage level ofthe uni-junction transistor this transistor lires. The number of currentpulses which are stored by the decade box capacitors before firing ofthe uni-junction transistor is determined by the settings of the decadebox switch, which settings are made in accordance with the nominalthickness of the particualr material being processed. For example, ifthe material has a thickness of 0.50 mil. the switches would be set sothat the uni-junction transistor will lire, say, after l2() chargingpulses have been applied to the capacitors. On the other hand, for amaterial having a thickness of 16.0 mils, the switch settings would besuch as to require only 3 charging pulses to cause firing of thetransistor. Upon each firing of the uni-junction transistor, the secondHip-flop circuit produces a corresponding output voltage pulse ofpredetermined height and width. These pulses are amplified and appliedto the stepping motor, thereby causing rotation of the arm of thecontrol potentiometer in a step-by-step manner. The added resistanceinserted into the circuit of the mandrel drive motor effects a reductionin the speed of rotation of the mandrel. It will be apparent, then, thatalthough the frequency of the initial signal pulses varies with thespeed of rotation of the mandrel, the slow-down of the mandrel iseffected in a step-by-step manner at a rate which is related to thematerial thickness, that is, in correspondence with the predeterminedincrease in the diameters of the rewound rolls.

The winding cycle is completed when the rewound rolls have a desireddiameter. The operator then operates the switches to stop the mandreldrive motor and the main motor of the machine. Next, upon the momentarydepression of the reset switch, the control circuit is changed so thatthe uni-junction circuit becomes an oscillator, thereby effecting rapidrotation of the stepping motor. At the same time, the electro-magneticclutches are actuated to effect a reduction in the gear ratio betweenthe arm of the control potentiometer and the stepping motor and toreverse the direction of rotation of the potentiometer arm. Upon thereturn of the potentiometer arm to its initial starting position, thesignal lamp is energized and the control circuit becomes dormant untilthe main drive motor and the mandrel drive motor are energized for thenext winding operation.

In a duplex machine having two rewind mandrels these mandrels generallyare coupled together for rotation by a single mandrel drive motor. Thus,only one control potentiometer is required to effect a slow-down of bothmandrels in a predetermined manner and in correspondence with theincreased diameters of the rewound rolls.

Having now described the invention, those skilled in this art will beable to make various changes and modifications Without thereby departingfrom the spirit and scope of the invention as recited in the followingclaims.

I claim:

1. Apparatus for automatically reducing the speed of a motor drivenmandrel carrying a core upon whi-ch a strip of material is to be wound,which apparatus comprises,

(a) a switch mechanically coupled to the mandrel,

(b) a first means producing first volt-age pulses in correspondence withthe opening and closing of said switch,

(c) a second means converting the said first voltage pulses into secondvoltage pulses having a predetermined height and width,

(d) a third means producing a control voltage pulse for a predeterminednumber of the second voltage pulses,

(e) a stepping motor energized by the control voltage pulse said motorhaving a shaft which rotates a predetermined angular extent upon eachenergization of the motor,

(f) a motor control potentiometer having a rotatable arm,

(g) coupling means mechanically coupling the stepping motor shaft to therotatable arm of the potentiometer for rotation in a predetermineddirection, and

(h) means connecting said potentiometer into the circuit of themandrel-driving motor so as to reduce the speed of such motor uponrotation of the said rotatable arm of the potentiometer.

2. The invention as recited in claim 1, wherein the said coupling meanscomprises,

(a) a first speed reducer having an input shaft coupled to the steppingmotor shaft and an output shaft,

(b) Ia second speed reducer having lan input shaft coupled tothe outputshaft of the first speed reducer and an output shaft,

(c) a first electro-magnetic clutch adapted when energized to connectthe output shaft of the second speed reducer to the rotatable arm of thepotentiometer, and

(d) a second electro-magnetic clutch adapted when energized to couplethe output shaft of the first speed reducer to the rotatable arm of thepotentiometer,

the arrangement being such that energization of one or the other of thesaid clutches produces rotation of the potentiometer arm in one or theother direction.

3. The invention as recited in claim 1, including manually-adjustablemeans to change the ratio between the number of said second volt-agepulses and the control voltage pulse.

4. The invention as recited in claim 3, wherein the saidmanually-adjustable means includes reference means for setting themanually-adjustable means in accordance with the thickness of the stripof material to be wound on the core.

5. The invention as recited in claim 1, wherein the said first meanscomprises a first capacitor and a charging circuit; wherein the saidsecond means comprises a flip-flop circuit responsive to each chargingcycle of said first capacitor, wherein the said third means comprises aunijunction transistor having a predetermined peak point voltage; andincluding a plurality of inter-connectable capacitors,manually-adjustable means to connect said plurality of capacitors toform a resultant capacitor, circuit element for charging the resultantcapacitor by the said second voltage pulses, and means connecting saidresultant capaictor to said uni-junction transistor to effect firingthereof when the voltage charge on said resultant capacitor reaches thesaid peak point voltage.

6. The invention as recited in claim 5, including reference meansassociated with the said manually-adjustable means, said reference meansbeing calibrated in factors related to the thickness of the strip ofmaterial to be wound on the core.

7. The invention as recited in claim 1, including manually operablereset means, circuit elements operable upon operation of said resetmeans to effect a reverse rotation of the potentiometer rotatable arm.

8. In a winding machine of the class having a motordriven mandrelcarrying a plurality of cores upon which strip-s of material are to `bewound, the combination of,

(a) a set of contacts which open and close in correspondence with therotation of the mandrel,

(b) a capacitor and a source of charging voltage, said capacitor beingcharged and discharged in correspondence with the opening and closing ofsaid set of contacts thereby producing signal pulses,

(c) means converting said signal pulses into square wave voltage pulseshaving a constant amplitude and width,

(d) a plurality of capacitors selectively connectable to form aresultant capacitor,

(e) circuit elements applying the square wave pulses across the saidresultant capacitor,

(f) discharging means for discharging the said resultant capacitor whenit has been charged to a predetermined voltage level,

(g) means responsive to eachdischarge of said resultant capacitor toproduce control voltage pulses,

(h) means amplifying the control voltage pulses,

(1) a stepping motor energized by the control voltage pulses, said motorhaving a shaft,

(j) a potentiometer having a rotatable arm,

(k) first and second speed reducers coupled together, the first speed,reducer being directly coupled to the stepping motor shaft and thesecond speed reducer l l being coupled to the rotatable arm of thepotentiometer through a rst electro-magnetic clutch,

(1) a second electro-magnetic clutch for coupling the tirst speedreducer to the rotatable arm of the potentiometer through a directionreversing means,

(m) means energizing the said tirst clutch when the mandrel drive motoris energized, whereby the potentiometer arm rotates in one direction,

(n) circuit elements connecting the potentiometer into the controlcircuit of the mandrel drive motor to reduce the motor speed as thepotentiometer arm is r0- tated in said one direction,

(o) manually-operable reset means for de-energizing the mandrel drivemotor and the said rst clutch, and for simultaneously energizing thesaid second clutch, and

(p) means effective upon operation of said reset means to apply a rapidsuccession of control voltage pulses to the said amplifier therebyresulting in a reverse rotation of the potentiometer arm toward itsinitial position.

9. The invention as recited in claim 8, including `signal means actuatedupon the return of the potentiometer arm to its initial position.

10. The invention as recited in claim 9, wherein the 2a said pluralityof capacitors are disposed Within a case and 1.2 are selectivelyconnectable to form the resultant capacitor by a plurality of rotaryswitches, and wherein the rotatable -member of each switch is alignablewith associated reference markings whereby the capacity of the resultant5 capacitor can be varied in accordance `with the nominal thickness ofthe strips of material to be wound on the cores.

11. The invention as recited in claim 9, including a normally-closedlimit switch connected in the circuit of 10 the mandrel drive motor, andmeans opening said limit switch when the rotatable arm of thepotentiometer is rotated beyond a predetermined point in the said onedirection. l

References Cited 15 UNITED STATES PATENTS 2,798,677 7/1957 Nicholson242-7551 XR 3,100,554 8/1963 Doubek 2.42-75.44 XR 3,114,850 12/1963Hansen 318-6 XR 3,151,507 lO/1964 Canova et al. 318-7 XR 3,214,11010/1965 Ross 242-7551 XR 3,223,906 12/1965 Dinger 242-7551 XR 3,248,6214/1966 Carter et al. 318-6 ORS L. RADER, Primary Examiner.

G. SIMMONS, Assistant Examiner.

